A man was rescued from inside a garbage truck in San Francisco after becoming trapped beneath piles of trash early Wednesday morning, setting off a difficult rescue that took more than two hours.

The San Francisco Fire Department was alerted around 4:11 a.m. on Wednesday, Sept. 2, after someone heard a man shouting from inside a Recology garbage truck.

According to SFFD public information officer Capt. Mariano Elias, the truck had already made its first stop of the morning and the driver had compacted the trash once.

A person walking nearby then heard someone yelling from inside the truck and quickly alerted the driver before another load of garbage could be emptied into it.

The driver shut off the vehicle and soon heard the trapped man screaming for help.

Because the man could not climb out on his own, and firefighters determined it would be too dangerous to simply dump the truck’s contents onto the street, crews had to carefully dig through the garbage to reach him.

Around 25 firefighters spent more than two hours working through the compacted trash.

Throughout the rescue, the man remained conscious and was able to speak with emergency crews.

“I personally heard him yell a few times,” Elias told PEOPLE. “I don’t know if that was in pain or just frustration.”

While firefighters worked to free him, paramedics were able to reach one of the man’s arms and start an IV to help protect him from crush syndrome.

Crush syndrome is a potentially life-threatening condition that can happen when prolonged pressure damages muscle tissue. According to the Centers for Disease Control and Prevention, damaged muscle can release harmful substances and electrolytes into the bloodstream, potentially leading to tissue injury, organ problems and dangerous metabolic complications.

The man was finally removed from the truck shortly before 7 a.m.

Elias said the victim was “awake and oriented” when rescuers got him out.

He was then taken to Zuckerberg San Francisco General Hospital, where he was listed in serious condition, according to a hospital spokesperson cited by The San Francisco Standard.

Officials believe the man had originally been inside a dumpster before the dumpster was emptied into the garbage truck.

“It’s an unfortunate situation to lead someone to go into a dumpster, whether that was to sleep or fish through some things to find something for himself or something to eat, but the good part of his outcome is that he’s alive,” Elias told PEOPLE.

Recology spokesperson Robert Reed told The Standard that the incident was highly unusual.

He said the last similar incident involving the company happened about 15 years ago.